On the creep force distribution law and dynamics of elastically constrained wheelsets under complex conditions

Railway vehicles sometimes operate under complex conditions, such as traction or braking, while navigating curved sections. These conditions result in steady longitudinal and lateral creep forces acting simultaneously on the left and right contact zones of the wheelsets. Owing to the nonlinear characteristics inherent in wheel-rail creep forces, these steady creep forces are unevenly distributed between the two contact zones, influencing the dynamics of the wheelsets and vehicle. It has been observed that identical increments in creepage generate smaller corresponding increases in creep forces when steady creep forces are present. In this study, the distribution law of steady creep forces between the left and right contact zones of an elastically constrained wheelset under complex conditions was analytically examined. Subsequently, the wheelset dynamic functions in the equilibrium position are established based on the distributed steady creep forces. The hunting stability and dynamic acceleration responses induced by track irregularities were analyzed under these conditions. The results indicate that under complex conditions, the longitudinal and lateral creep forces are coupled and significantly affect the wheelset dynamics. It was also demonstrated that the braking torque consistently enhances the dynamic performance, whereas the traction torque may occasionally negatively affect vehicle dynamics.